I Actually asked the same thing when I was looking for Oreo's Companion. I didn't want to get a boy because since Oreo was Alpha Male.. he's get quite jealous. he Was 4 months old when we Got Ginger, And she was also 4 months old at the time.. And we just added a new Member, a new baby girl only 10 weeks and so far so good.
I'm not planning on Spaying/Neutering My dogs, call me crazy, but i don't want to, there will be people who will tell me to, object with me.. but it's my decision, none of my dogs are going to the shelter either, so i'm not worried.
But I think it's a great thing your getting a companion for Jo-Jo! Oreo was so lonely, i couldn't ever leave him alone! but once I Got Ginger, it was like they didn't need me!.. only for belly rubs, food, potty etc..

they are even more happier i got a third!
So good luck when you do get yours, whichever Gender you decide!